试验及实际运行经验表明,接地装置冲击特性是影响输电线路耐雷性能的重要因素.笔者以土壤电离过程中的动态、分布式土壤参数为基础,对典型接地装置建立冲击特性有限元模型;根据仿真计算结果与模拟试验结果从电磁场角度分析了典型接地装置的冲击散流机理及散流规律;同时定量计算了冲击电流作用下土壤参数及注入电流参数对土壤电离区域体积的影响规律,在此基础上分析了土壤电离对典型接地装置接地电阻、跨步电压、接触电压等接地参数的影响.结果表明,土壤电离现象对冲击散流特性和冲击接地参数的影响在高幅值注入电流、高电阻率地区更明显.该研究结果可为输电线路冲击接地降阻新措施的提出提供理论支持.
The tests and actual operating experience show that the impact characteristics of grounding device characteristics are important factors about lightning protection performance of transmission lines. In this paper, based on the dynamic soil ionization process and distributed soil parameters, we established the finite element model of the impulse characteristics of grounding device. According to the simulation results and test results, we analyzed the mechanism and law of diffuser impact about typical grounding device from the electromagnetic field. And we calculated quantitatively the influence of the soil parameters and injection current parameters to the soil volume ionization region under the impact of current action. On the basis of these, we also analyzed soil ionization effect on typical ground resistance, step voltage, contact voltage and other parameters of the ground. The results show that the soil ionization phenomena has a great influence on the impulse diffuser char- acteristic and impulse grounding parameters, especially in the area of high resistivity and high injected current. the findings can provide theoretical support for new measures of reducing the impact grounding resistance.